1. Field of the Invention
The present invention relates to a no-backlash gearing mechanism.
2. Discussion of the Related Art
A no-backlash gearing mechanism is disclosed in United Kingdom patent specification No. 1 251 941 in which the teeth of at least one of a pair of meshing toothed elements are formed of elastic rubber or plastics material and may additionally be formed with slots or bores to improve their deformability. By urging the toothed elements together when meshing, the deformable teeth of one element fully mesh with the teeth of the other element without back-lash. However, this gearing arrangement is only suitable for very light loads since, due to the deformability of the teeth, slippage of the meshing toothed elements can occur.
European patent specification No. 0 084 197 also offers a solution to the problem of back-lash in gearing mechanisms. The gearing mechanism of EP 0 084 197 comprises a pair of meshing toothed elements, each of which have teeth of transverse asymmetrical shape which, when meshing, are urged into contact with each other in a direction normal to the plane of rotation of the toothed elements. In addition, the teeth of the toothed elements may be slotted to improve their deformability and thus ensure no-backlash. This arrangement necessitates the inclusion of means for urging the meshing toothed elements into contact in a direction normal to the plane of rotation of the toothed elements.
United Kingdom specification No. 1 202 806 also offers a solution to the problem of back-lash in gearing mechanisms. The solution discussed is even more similar to that of GB 1 251 941 than that of EP 0 084 197. The gearing mechanism of GB 1 202 806, whilst being an internal/ring gear mechanism, utilises the principle of having a first meshing toothed element with teeth formed of deformable material urged into meshing engagement with a second toothed element, wherein the deformable teeth, when meshing, deform to completely mesh with the teeth of the second toothed element thereby preventing back-lash. This gearing mechanism is also susceptible to slippage due to the high deformability of the teeth.